Pindal cave, listed as World Heritage by UNESCO since July of this year, can tour in 3D thanks to a research by a team of professors at the Polytechnic School of Avila, who heads Diego González Aguilera.

This team, known as Tidop Research Group (Information Technology for Heritage Documentation) just completed under the supervision of Professor Mario Menéndez, Department of Prehistory and Archaeology at UNED, its comprehensive documentation and metric 3D reconstruction. But what is the real importance of this work? “The determination of the geometric component in the accurate documentation of the heritage involves the quantification of the special characteristics of the object, especially its shape and dimensions, orientation and location”, profesor González Aguilera explains, “and this operation becomes important in the sense that their results may become the basis for reconstruction and is also a testimony of the prior state to any intervention or modification.” Pindal cave stands in the vicinity of the town of Pimiango in Ribadedeva (Asturias), near the border with Cantabria. This beautiful corner is well known for some cave paintings discovered in 1908.

Terrestrial laser scanner

Recently, the use of terrestrial laser scanner, used in researchs, enables a new approach to the problem of documentation and three-dimensional geometric modeling of the Paleolithic caves and parietal art. According to the studio manager says, this is the land Trimble GX scanner mounted on the Manfrotto 400 swivel that allows spins with three degrees of freedom, necessary to accommodate the position of the scanner to the characteristics of the cave. “The data captured by this team is finally summarized the three-dimensional XYZ coordinates of mesh points and their radiometric values in RGB color system,” points out the technical details González Aguilera. Basically this laser and two high resolution digital cameras were the tools needed to carry out the fieldwork. “The field work was conducted for five alternate days. They included five members of the group Tidop aided by two operators of the Council. “Thus it was possible to combine the laser scanning and the photo shoot,” says González Aguilera, further explains that, given the complexity of the geometry inside the cave and the problems caused by occlusions, both for laser scans as for photographic archive was necessary to make a total of 19 laser stations, from which they made general scans of 360º with mesh steps of 2 centimeters in 20 meters, and two shots per point. “This data collection configuration ensured more than 15% of overlapping between the point clouds obtained, thereby having a guarantee for proper fusion of the point clouds”, says the professor of the Polytechnic. In fact, a total of 33 million points in XYZ coordinates were obtained for the geometrical definition of the interior of the cavern. On the other hand were the photo sessions that involved two different types of work: a set of shots to complete the work of the laser, through the ability to provide high-resolution photographic texture to the point cloud, and another set of shots with the fisheye lens for the generation of linked panoramas that allow us to generate a virtual visit. For this 25 photographic stations were chosen from which we made the seven necessary shots to compose each of the 25 panoramas.

Computer processing

After the processing of all the data the team obtained a ground orthophoto. “It shows a top view of the cave, which can be considered as a precise and detailed plan of the cave”, begins to list his conclusions Professor González Aguilera. Furthermore, orthophotos of the cave paintings room and a textured 3D model were obtained. “This is an interactive model through which you can navigate, retaining the metric properties and being able to see the object from inaccessible points of view,” says the teacher, pointing this advantage of the system. Diego González Aguilera explains that from the data obtained has been possible to draw another set of tools and applications that have resulted in obtaining virtual flights, that is, a number of video files generated from the laser three-dimensional models, as well as a virtual tour that has been generated by coherent composition of the whole panoramic photographs taken before and also has been able to generate transverse and longitudinal sections of the cave. With this work done in the environment that will, among other things, better and wider dissemination of the cave is complete. With this the work is completed and it will allow, among other things, a better and wider dissemination of the cave.

The walls of Ávila, the aqueduct of Segovia and Schoolyard of Salamanca undergo a virtual accessibility project designed by Polytechnic School of Ávila.

The walls of Ávila, the aqueduct of Segovia, the Roman city of Clunia in Burgos and Schoolyard of the University of Salamanca will no longer be inaccessible heritage assets for people with disabilities through the work of TIDOP – Information Technologies for the Heritage Documentation – Polytechnic School of Ávila, attached to the University of Salamanca, and a virtual accessibility in 3D project from a technology that has dubbed “The digital dream”. The group where working on the ‘Sv3Dvisión’ initiative for five years and they presented it in Salamanca under the Virtual Reality and Leisure Fair, organized by the Recovery Center for Persons with Physical Disabilities (CRMF). It uses digital cameras, a laser scanner with a 350 meter beam and a panoramic camera from which capture “impossible views” to digitize and make virtually accessible the most important heritage of Castilla and León, said Diego González Aguilera, one of the members of TIDOP. Thanks to the combination of these three sensors not only get the 3D reconstruction outside the monuments or archaeological sites, they also make a “radiography of their structure to see the skeleton of the monument” and get measurements that are useful for experts enabling them to know details that, in the case of the walls of Avila, goes from the height of the monument, the size of the stones through the width of the battlement.

In addition, the project is also designed to ‘navigate’ through the assets, even reaching to areas restricted for general public access – Las Caldas cave (Oviedo) – incorporate elements that once existed but now gone – Celt caves in the Castro of Cogotas (Ávila) and roman City of Clunia (Burgos) – and even get information on anything that is within a construction – Romanic Church of San Pedro of Ávila- from a frame to the temple belfry . Part of the assets addressed by the TIDOP Group is accessible via the internet address www.usal.es/imap3d

Without barriers

González Aguilera explained that thanks to technology baptized ‘The digital dream’ is achieved both overcome architectural barriers, such as geographical and temporal plus spatial and protection barriers, linked to limited access to the monuments. In the case of architectural barriers, professor of the Polytechnic School of Ávila said that thanks to the technology used and through the images taken from air and land are reconstructed in 3D the most important monuments and made them accessible through Internet, including information in text format in its most significant elements to which the user can access only clicking the mouse. As stated, ‘The digital dream’ also overcomes geographical barriers in the case of inaccessible constructions or deposits such as the Ulaca castro (Ávila) whose contemplation requires walking up for 20 minutes for the mountain- and also jump barriers temporary. So, he referred to the work in archaeological sites and findings of human remains, which surveys are conducted and finally capped. In this way, he highlighted the work done by the Group in Jewish tanneries of San Segundo (Ávila) and the Roman town of “San Pedro del Arroyo”, where an iconic mosaic and several rooms was found that, as in the tanneries, were excavated and then covered to prevent spoliation. However, they can be visited thanks to its 3D reconstruction. As for overcoming spatial barriers, Diego González Aguilera insisted that the work is useful for both people with disabilities and for those that are not, because thanks to the installation of a camera to “remote sites” -at 70 meters of high- is achieved to generate “impossible views” of the monuments that would be impossible to access with conventional technology. It is the case of the work done in the Cloister of Silence monastery of Santo Tomás in Ávila, where visitors can “dive” and see the “skeleton” of the monument. The professor of the Polytechnic of Ávila added that the designed system facilitates also omit the called “protective barriers” which are those that exist on Palaeolithic and prehistoric caves to which the public has restricted access. This technology allows to do a replica of them and document corners to which man has not yet come. This is the case of Las Caldas cave in Asturias, where entry is prohibited and thanks to the laser scanner is accessed to galleries where the prehistorian has not arrived yet, he said. González Aguilera emphasized the positive reaction of the disabled people after the project presentation. As stated, the Virtual Reality Fair provided a framework for presenting new techniques to operate a computer without a mouse,with the eyes, depending on the blink, “very interesting technological devices for people with a high degree of disability.” From their point of view, the result of the combination of both technologies “can be tremendous.”

Almost all Ávila

About the work of the TIDOP Group – Javier Gómez Lahoz, Ángel Luís Muñoz Nieto, Jesús Sabas Herrero and Diego González Aguilera, in the last years and thanks to an important part of final year projects, they have touched heritage assets of almost all the provinces of “Castilla y Leon” While ” Ávila is almost completely digitized ” in Burgos has been digitized the Roman City and the Clunia theater and in Salamanca the schoolyard and Little Schools. Currently they are working on the aqueduct of Segovia and several chapels in the province. Regarding future projects, the group has received offers to work in part of the city wall and part of the Cathedral.

digital dream

Researchers at the University of Salamanca generate three-dimensional environments and multimedia of the archaeological heritage of Castilla y León.

Seen from impossible perspectives the vaults of the cathedral of Zamora, walk through hidden nooks of the 2,500 battlements of the walls of Ávila or enjoy a bird’s eye view of the Charterhouse of Miraflores in Burgos could become reality thanks to initiatives such as the one developed by the Group of Information Technologies for the Heritage Documentation at the University of Salamanca (TIDOP). The researchers team, led by Professor Diego González Aguilera, works to spread the Architectural and Archaeological Heritage of Castilla y León through the generation of virtual reality environments with multimedia content. New technologies have been crucial in overcoming architectural, geographical and time barriers for people in general, especially for those who have some type of disability. To date there have been many and varied performances from TIDOP group to eliminate these limitations. His works reconstruction of the walls of Ávila or the hermitage of San Benito Abad (Navarredonda de Gredos) are remarkable, besides the virtual three-dimensional interactive graphics recreation of the roman city of Clunia and many vetone castros, places of cultural interest whose location in inaccessible places preclude their visit.

There are numerous his technical support to public entities such as the “council and the local government of Ávila”, in the context of archaeological research conditioned by reasons of urban planning and construction that after the field work will be covered again. Thanks to his digital documentation techniques have safeguarded the three dimensional configuration of sites such as the medieval tanneries of Ávila or the roman Town of San Pedro del Arroyo. Digital reconstructions of these spaces have allowed archaeologists and historians to have metric documentation for virtually recreate and preserve their spatial geometry, thus overcoming the time barrier.

The photogrammetric technologies associated with information and communication technologies allowed to advance in the overcoming spatial barriers. One of them, imposed on each of us as a result of our stature, is the immovable point of view with which we can see everything. Fact that limits the knowledge and enjoyment of cultural goods and makes always consider from the same perspective. This ‘handicap’ was mitigated by actions such as those undertaken by researchers at the University in virtual reconstructions developed under the exhibition “Las dos Orillas”, commemorating the fifth anniversary of the death of Christopher Columbus, and the work focused in the chapel of Our Lady of Sonsoles or St. Nicholas Church. Jobs that concluded in interactive graphic products in which the user can vary the point of view virtually placing it in a bird’s eye view and enjoy unreachable areas and details with a naked eye.

The solutions of the TIDOP Group also have been required by administrations forced to take stringent conservation measures in some heritage assets restricting and even forbidding access to them. An example is the metric documentation developed in the caves of the Asturian Paleolithic of “Calda” and “Peña de Candamo”, which has allowed the virtual recreation with a high degree of detail of the volumes of the walls. Recreations that then were disseminated through publications and international conferences for knowledge of the scientific community.

The use of infrared thermography as a widely tested technique for building inspection and location of pathologies such as air leakage and moisture allows the performance of quality “in-situ” visual examination of the objects under study due to the possibility of obtaining real-time results, being able to detect without difficulty damages or material characteristics. This qualitative measurement technique provides the capability of doing quick, effective and non-destructive inspection without direct contact with the object under study, decreasing the risk of incidents to operators and the damage of the objects comparing with other intrusive techniques. Furthermore, the utility of infrared thermography as a measurement technique has been proved by its use for the determination of the thermophysical properties of materials such as diffusivity and thermal transmittance.

In the qualitative approach, some authors have performed in-situ studies, mainly in historical buildings or cultural heritage elements, whereas quantitative studies are performed mainly in laboratories with limited size samples. In those cases where quantitative thermography studies were performed in-situ, temperature values were employed in order to obtain the real thermophysical properties (thermal conductance) of the building envelope, but their spatial distribution is not considered.

Combine both applications will enable the automation of the heat loss computation from the measured temperatures with a thermographic camera. Thus, the thermography is not only used to represent the state of the wall, but also temperature values represented on the thermography for extracting the metric parameters of the study object so the hybridization of the thermographic information with precise cartographic material would allow to extract the actual geometry of the object of study with thermal texture, being able to make accurate measurements of the elements of interest directly on the obtained results.

Studies such as the one published by EuroACE in 2010, places improved energy efficiency in building construction at the top of the list of actions that need to be taken to reduce greenhouse gases and energy costs, in addition to acting as a stimulus to generate employment. In particular is the case of existing buildings stock, most of which dates back to the period 1940-80, constructed using non-existent standards and scarce resources. Here, energy refurbishment works could represent a saving of up to 75% in energy consumption. In Spain there are 13 million homes that could be the subject of intervention, where energy refurbishment could result in a reduction in sector emissions of 34% compared to 2001.

In urbanized Western Europe trees are considered an important component of the built-up environment. This also means that there is an increasing demand for tree inventories. Laser mobile mapping systems provide an efficient and accurate way to sample the 3D road surrounding including notable roadside trees. In this research line, a processing chain aiming at the extraction of tree locations and tree sizes from laser mobile mapping data is reached.

Vegetation extraction

Tree parameter extraction

Such steps, in combination with code optimization are expected to be sufficient to reach the final goal of automatized estimation of features sampled by mobile mapping at a rate that matches the acquisition speed and at a quality that matches the result of a human operator.